Development of 40 GW repetitive pulsed driver is summarized in this report. The output of the 40 GW repetitive pulsed driver source is aimed to exceed 40 GW, the pulse width is about 60ns, and the range of repetition rate is set from 1 pps to 50 pps. Based on the Tesla technology, the general design of the 40 GW driver source is described. The accelerator was assembled and an experiment was performed for generating high power microwave. For charging the forming line, a Tesla transformer with open magnetic core was used, a high efficiency about 70% of the transformer was achieved by means of optimization. As an electron beam source, the output of the 40 GW driver source is more than 40 GW. With 50 Hz repetition rate, the mean power of the diode has exceeded 20 GW. Operation experiments have